I HAVE A 91 GTA L98 TPI i remover the upper plenum runners and intake manifold,ported polished and gasket matched all the intake installed (egr delete plate )plugged vacuum lines. i also reset timing 6deg btdc i was informed that just deleting the egr can cause problems due to the ecm controlling the egr so i am now faced with the problem of having my pcm flashed to remove the egr air circuit or buy a (pill/chip) to fix the problem but don't know which chip manufacturer i should go with or which stage it should be any help would be great

 

Your computer has a removable memcal ( prom ) so it can't be "reflashed" in place like later model cars.
I would drive the car and see if you get a EGR code showing up ;some do and some don't.
In any case it won't have any effect on the engine operation; is just a code saying the computer is not seeing the EGR operating because it is no longer there.
Any of the online mail order tuners car do you a new tune with the EGR deleted but you can also get other things done at the same time for same cost,
VATS delete , change fan operating temps , etc